The sowing date of maize significantly impacts its main yield elements. The experiment, conducted at the Research and Development Station for Cattle Breeding (R.D.S.C.B.) Târgu Mureș, Sângeorgiu de Mureș, România, from 2018 to 2021, involved nine maize hybrids from different maturity groups, sown on three dates: early sowing (ES) at 6 °C soil temperature, optimal sowing (OS) at 10 °C soil temperature, and late sowing (LS) two weeks after the optimal date. The experiment was placed in a poly-factorial experience of type: A × B × C × C − R: 3 × 9 × 4 − 3, organized according to the subdivided plots method. The study examined the influence of sowing date on grain yield (GY), thousand-kernel weight (TKW), test weight (TW), percentage of grains per cob (% G/C), and grain humidity at harvest (GHH). The results indicated that yield was not negatively impacted by early or late sowing compared to the optimal date, with differences of 52 kg ha⁻¹ between ES and OS, 147 kg ha⁻¹ between ES and LS, and 95 kg ha⁻¹ between OS and LS. ES increased TW (723.4 kg hl⁻¹) and % G/C (86.7%), but reduced GY (13,377 kg ha⁻¹), TKW (335.3 g), and GHH (19.5%). Conversely, LS positively influenced GY (13,524 kg ha⁻¹), TKW (356.7 g), and GHH (23.9%), but negatively affected TW (692.8 kg hl⁻¹) and % G/C (84.9%). Yield data obtained by P9900 and Kapitolis hybrids suggest that they are suitable for early sowing.

This study aimed to investigate the effects of different nitrogen (N) fertilizer rates and sowing dates on grain yield, protein content, grain N uptake, and nitrogen recovery efficiency (NRE) in spring and facultative wheat (Triticum aestivum L.) cultivated in northwestern and central Romania from 2018 to 2020. The experiment was designed as a split–split plot study with two spring sowing dates (SDs): an optimal date (1–15 March) and a delayed date (postponed by two weeks). All treatments received a basal autumn fertilizer supplying 36 kg N ha⁻¹ and 92 kg P ha⁻¹. In spring, three N treatments were evaluated: no additional N (N₃₆), 72 kg N ha⁻¹ (N₁₀₈), and 105 kg N ha⁻¹ (N₁₄₁), with the supplementary N top-dressed at the booting stage. The results showed that delayed sowing significantly altered grain N uptake dynamics and reduced NRE, even under standard fertilization regimes. Specifically, delayed sowing reduced grain yield by 7.52% to 28.39% compared to optimal sowing, while adverse climatic interactions in delayed setups reduced the mean NRE to as low as 16.43%. These findings indicate that conventional N application strategies may be suboptimal under variable sowing conditions and highlight the importance of adaptive N management to improve both agronomic performance and environmental sustainability.